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    <title>Document</title>
    <script>
        //1.新增数组元素修改length长度
    var arr = ['red','green','blue'];
    console.log(arr.length);
    arr.length = 5;
    console.log(arr);
    console.log(arr[3]);
    console.log(arr[4]);
    // 2.新增数组元素  修改索引号
    var arr1 = ['red','green','blue'];
    arr1[3] = 'pink';
    console.log(arr1);
    arr1[4] = 'hotpink';
    console.log(arr1);
    arr1[0] = 'yellow';//这里是替换原来的数组元素
    console.log(arr1);
</script>
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